The subject invention has utility in various tufting systems, however, it has particular utility when used with the "Spanel tufting systems" which utilizes pneumatic transportation means for transporting yarn to the tufting stations.
The basics of the "Spanel tufting system" are disclosed in U.S. Pat. No. 3,554,147 which issued to Abram N. Spanel and George J. Brennan on Jan. 12, 1971 and U.S. Pat. No. Re 27,165 which issued Aug. 10, 1971 to Abram N. Spanel and Loy E. Barton. The aforementioned U.S. Pat. No. Re 27,165 discloses a pneumatic yarn transport system in which yarn is transported pneumatically to a tufting station where it is applied by tufting elements to a backing layer after being severed. Multicolor selection of the yarn bits is provided and for each needle station a choice of a number of colors is available.
The aforementioned U.S. Pat. No. 3,554,147 describes an alternative system to U.S. Pat. No. Re 27,165 and provides for the simultaneous selection of bit lengths of yarn of various colors for each tufting cycle at each individual tufting station. A collator structure is utilized in which individual channels transport yarn into a common passageway adjacent the tufting station. In the preferred embodiment, the severing function takes place in close proximity to the tufting station after a selected yarn strand has been fed into the common passageway.
As disclosed in co-pending patent application Ser. No. (S-168), an improved cutter mechanism is disclosed wherein yarn strands are transported to the tufting station and by means of reciprocating travelling knives which coact with a stationary blade, yarn is severed prior to tufting.
A tufting machine may have as many as 1200 individual tufting stations with each tufting station comprising a dual shank needle as described in U.S. Pat. No. Re 27,165. With yarn being fed to each of as many as 1200 needles, it is necessary that the yarn be correctly metered and that the cutter mechanism as described in co-pending patent application Ser. No. (S-168) be appropriately adjusted so that the yarn is severed at each needle station properly without failure. If the severing is not properly done, jamming and related malfunctions will occur. It is important that such malfunctions be detected immediately and the machine stopped to permit the defect to be corrected. Since yarn is comprised of many filaments and in view of the difficulties with severing a strand projected through a knife station but unattached at its downstream end, an extremely proficient cutter mechanism must be utilized. It is also equally important to detect malfunctions as they occur so that the machine may be immediately stopped and remedial action taken.